A novel method of allelic exchange has been developed. This method is demonstrated in E. coli with the use of a mutant luciferase gene which has a termination codon placed in frame at the glutamine 143 amino acid. A conversion of this termination codon to the glutamine 143 found in wild type luciferase was demonstrated in E. coli. The exchange required the use of an oligonucleotide and the very short repair enzyme, (vsr). Through an unknown mechanism, an oligonucleotide with the correct sequence to restore glutamine 143 was capable of binding to its complimentary strand and the vsr enzyme enabled the exchange of genetic information between the two different genes. However, efficiency of exchange does not appear to be very high, since postexchange luciferase activity of mutant luciferase is only 0.15% of the activity found after transfection of the normal gene. Continued work may improve the system's abilities and allow it to work in mammalian cells and improve the efficiency of the exchange.